Comment 4 for bug 2055806

More discussion threads regarding this issue.

This is an old one from 16.04 before ssh socket activation.

https://askubuntu.com/questions/1110828/ssh-failed-to-start-missing-privilege-separation-directory-var-run-sshd

Another older report from 5-years ago from 16.04.05 again.
https://askubuntu.com/questions/1109934/ssh-server-stops-working-after-reboot-caused-by-missing-var-run-sshd/1110843#1110843

Below is an older report from 16.04.05 that probably resulted in the creation of /run/sshd/ by systemd-tmpfiles-setup.service

https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1811580

An even older bug regarding the same issue.
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/45234

Again it shows up.
https://serverfault.com/questions/941855/why-am-i-missing-var-run-sshd-after-every-boot